STRUCTURAL STEEL STANDARDIZED CARGO VESSELS. 105 



accuracy of fit. In brief, this necessitated the eHmination of curves and the substitu- 

 tion of straight lines and angles wherever possible. 



The decks are without camber and generally without sheer, the sides through- 

 out the length of the parallel body are perpendicular; the bottom is flat, and is 

 merged with the sides by a short and abrupt curved bilge. By eliminating the dead- 

 rise characteristics of the vessel it was possible to adopt a uniform size of floor 

 throughout the parallel body and to have recourse to longitudinals which would all 

 be of the same height. Forward and aft of the parallel body the model subscribes 

 with reasonable closeness to that of the accepted design of ocean-going carriers. 



The plans accompanying this article illustrate the details of construction and con- 

 tour of the vessel, which is pleasing in appearance, and from the tests made at the 

 Government Model Experimental Basin it was disclosed that the ships are rather eco- 

 nomical in their propulsive requirements, with a block coefficient of 0.78. Their drive 

 is as easy as the ordinary model of cargo carrier of like displacement and similar 

 speed. The effect of the usual sheer is obtained by giving the upper deck, forward, 

 a flat rise of 5 feet to the stem. This, with the usual flaring bow, gives the desired 

 measure of added buoyancy when driving into a head sea. The parallel middle body 

 constitutes about 43 per cent of the ship's total length. 



The principal dimensions and general characteristics are as follows (see Plate 

 81).— 



Length between perpendiculars 324 feet. 



Length over all, about 335 feet 6 inches. 



Beam, molded 46 feet. 



Depth at side to upper deck 28 feet 6 inches. 



Load draught, about 22 feet 1 1 inches. 



Number of propellers i 



Propelling engine, turbine of 1,500 horse-power. 



Speed 10^ knots an hour. 



Deadweight capacity S,ooo tons. 



As the plans disclose, the ships are constructed upon the transverse system of 

 framing, and the double bottom extends from the after peak bulkhead forward to 

 the collision bulkhead. There is but one complete deck, the upper deck, extending 

 from bow to stern. Without exception the decks are worked flat, both athwart- 

 ships and fore and aft. 



As quantity production was the keynote in building these ships, it was essen- 

 tial that the main propelling machinery should be of types capable of being manu- 

 factured in quantity. Therefore watertube boilers were chosen with reduction gear 

 turbines. The boilers are of the Babcock & Wilcox make with a total heating 

 surface of 5,800 square feet, operated with coal or fuel oil under natural draft. The 

 propelling machinery consists of a geared Westinghouse turbine capable of devel- 

 oping 1,500 shaft horse-power, turning a i5j4-foot, 4-bladed screw at 90 revolu- 

 tions per minute. The turbine is connected to the propeller shaft by a helical, 

 double reduction gear with a ratio of speed reduction of 40 to i. The steam 



